$.pair= $.klass();
$.pair.prototype=
{   init1: function( pair ){
        this.key= pair.key
        this.val= pair.val
        return this
    }
,   init2: function( key, val ){
        this.key= key
        this.val= val
        return this
    }
,   destroy: function( ){
        delete this.key, this.val
        return this
    }
}